The primary goal of this project is the delineation of the interactions of Neisseria gonorrhoeae with serum components and polymorphonuclear neutrophils. The emphasis of these studies is on the role of serum complement, of antibody and of neutrophils in the chemotactic, phagocytic and microbicidal responses to gonococci, which may be important in the pathogenesis of the different clinical syndromes of gonococcal infection. Results to date indicate that strains of gonococci isolated from patients with localized forms of gonococcal infection stimulate neutrophil chemotaxis more readily and are more readily phagocytosed than strains of gonococci isolated from patients with disseminated disease. These observations may relate to the relative paucity of genital symptomatology in patients with disseminated disease as well as to the pathogenesis of dissemination. Studies during the coming year will bear on factors which may be important in the attachment of gonococci to neutrophils; the physico-chemical properties of gonococci that relate to opsonophagocytosis; and the killing of gonococci by cell-free model neutrophil killing systems.